Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 290803
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
403 AM EDT Thu Jun 29 2017

.SHORT TERM...(Today through Friday)
Issued at 308 AM EDT THU JUN 29 2017

The ridge of high pressure that has brought dry and pleasant
weather to eastern Kentucky the past few days will finally break
down enough to allow a few showers and storms to move across the
Tennessee border and into eastern Kentucky later today. An area of
low pressure passing by to the south of the area will be the
trigger for any showers and storms that we see today. The first
precipitation should begin moving across the TN state line and
into our southern counties by late this morning. This activity
will increase in coverage this afternoon, and we may see scattered
showers and storms for a few hours along and south of the Hal
Rogers Parkway. The rain should be gone by 0Z, as we lost daytime
heating and low pressure moves off to our southeast. Another
better shot of rain is expected on Friday, as a second better
organized weather system moves out of the Tennessee valley and
across portions of eastern Kentucky. The best chance of rain with
this second system should be Friday afternoon.

Temperatures are expected to be around normal today and tomorrow,
with max values in the mid to upper 80s expected today, and the
lower 80s on Friday. Tonights lows will be a bit warmer as well,
with minimum readings in the mid to upper 60s expected along
ridges while the surrounding valleys fall into the lower 60s.
Winds should be out of the south at 5 to 10mph for most locations.
A few locations along and north of I-64 could see sustained winds
later today of around 10mph.

.LONG TERM...(Friday night through Wednesday)
Issued at 358 AM EDT THU JUN 29 2017

Increasing southwest flow will take shape Friday evening/night
across eastern Kentucky. Troughiness will extend south into the
Missouri Valley from a closed low in Manitoba, as a cool front
stretches from the Great Lakes into the southern Plains. The
approach of this front along with subtle height falls Saturday into
Saturday night will bring numerous showers and thunderstorms to
eastern Kentucky. Given surface-based CAPE values of near 2 kJ/kg
and deep layer shear of approximately 30 knots, could very well see
a quick uptick in updraft intensity out of any storm. This would
promote a few downburst wind gusts, but any semblance of a dry sub-
cloud layer appears pretty lackluster in terms of seeing much in the
way of any damaging gusts.

The threat of showers and storms will continue into the second half
of the weekend ahead of the greater moisture plume downstream of an
approaching surface ridge. Rising height fields, as the flow
aloft veers more zonal and large-scale difluence is lost, will
likely keep any precipitation confined to the higher terrain near
the Virginia state line. Airmass recovery remains questionable as
to thunder chances, especially given a relatively drier pocket of
air advecting in. Temperatures are still expected to warm into the
low-mid 80s as the northern extent of the core of the system`s
energy, coupled with high pressure from the western Atlantic into
the Gulf of Mexico, precludes a solid cool frontal push through
eastern Kentucky.

Northwest flow looks to keep conditions dry for Monday, before a
shortwave trough passes through the western CONUS ridge and moves
toward the Midwest. This will increase shower/storm chances for at
least Tuesday and likely Wednesday, with the evolution/digging of
the system determining how long into the week chances linger. Yet
another amplifying upper high will develop across the intermountain
West, potentially building east and sparking quite a warmup by the
latter half of the week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 200 AM EDT THU JUN 29 2017

VFR conditions will generally continue through early this morning.
Some patchy MVFR or worse fog will likely occur once again
between through 12z; however, this will be confined to the
deepest river valleys. Warm and moist return flow will bring some
scattered cumulus back into the area during the afternoon. A few
afternoon showers and storms will be possible mainly along and
west of I-75; however, given the expected limited areal coverage,
will continue to not mention at LOZ and SME. Light south winds
through Thursday morning will become south southwest at near 10
kts by the afternoon hours.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...AR
LONG TERM...GUSEMAN
AVIATION...AR



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